Pectin polymers are important constituents of plant cell walls. Pectin is a hetero-polysaccharide with a backbone composed of alternating homogalacturonan (smooth regions) and rhamnogalacturonan (hairy regions). The smooth regions are linear polymers of 1,4-linked alpha-D-galacturonic acid. The galacturonic acid residues can be methyl-esterified on the carboxyl group to a varying degree, usually in a non-random fashion with blocks of polygalacturonic acid being completely methyl-esterified.
Pectinases can be classified according to their preferential substrate, highly methyl-esterified pectin or low methyl-esterified pectin and polygalacturonic acid (pectate), and their reaction mechanism, beta-elimination or hydrolysis. Pectinases can be mainly endo-acting, cutting the polymer at random sites within the chain to give a mixture of oligomers, or they may be exo-acting, attacking from one end of the polymer and producing monomers or dimers. Several pectinase activities acting on the smooth regions of pectin are included in the classification of enzymes provided by the Enzyme Nomenclature (1992) such as pectate lyase (EC 4.2.2.2), pectin lyase (EC 4.2.2.10), polygalacturonase (EC 3.2.1.15), exo-polygalacturonase (EC 3.2.1.67), exo-polygalacturonate lyase (EC 4.2.2.9) and exo-poly-alpha-galacturonosidase (EC 3.2.1.82).
The international patent application published as WO99/27083 discloses a pectate lyase cloned from Bacillus licheniformis. The international patent application published as WO99/27084 discloses pectate lyases cloned from Bacillus agaradhaerens, Bacillus halodurans and other Bacillus sp.
Cloning of a pectate lyase from Bacillus subtilis has been describe in Nasser et al. (1993) FEBS 335:319-326. This pectate lyase requires divalent cations for maximum activity, calcium ions being the most stimulating.
JP 2000-262292A discloses a gene coding for Bacillus protopectinase, a transformant containing the gene, and refinement of fiber using the transformant.
U.S. Pat. No. 6,172,030 discloses a detergent composition containing a Bacillus protopectinase having optimum pH 7 or higher against protopectin and polygalacturonic acid substrates.
It is the object of the present invention to provide a pectate lyase enzyme having high performance in detergent compositions.